Heretofore, electrical discharge machines have typically included a servo driven head mounted thereon for guided movement in a vertical direction, with either a single electrode or a pair of like or different electrodes removably mounted via suitable quick change means on the driven head. An example of such a machine is set forth in U.S. Pat. No. 4,316,071 issued Feb. 16, 1982 to Bonga for Tool Changer. Other EDM machines have included a series of individual electrodes at different locations on a rotatable turret supported in turn by a servo driven head; an example of such a turret is shown in U.S. Pat. No. 4,459,410 issued July 10, 1984 to Inoue for a Method of and Apparatus for Machining a 3-0 cavity in a workpiece. While such arrangements are satisfactory, they do not incorporate means for mounting and indexing refeed type cartridge assemblies in order to permit flexible interchange of cartridges with different electrode types.